In a general semiconductor industry or a related industry to the liquid crystal display, a baking or pre-baking process is indispensable to the preparation of a substrate such as a wafer or a panel. The baking procedure is usually carried out before or after coating and after developing.
Please refer to FIGS. 1, 2A and 2B. FIG. 1 is a schematic structural diagram of a conventional oven apparatus 10 which comprises a hot plate 11, a lower plate 12 (shown in FIGS. 2A and 2B), an upper plate 13, a hollow shutter 14 and a linear air cylinder 15 of which the motion is linear. FIGS. 2A and 2B are respectively a top view of the oven apparatus 10 with the upper plate 13 removed and a cross-sectional view thereof along with a line AA′ of FIG. 1, wherein the lower plate 12 below the hot plate 11 is made of stainless steel and is fixedly connected to the hot plate 11, and the hot plate 11 is placed at an appropriate position in the hollow of the shutter 14.
The shutter 14 of the conventional oven apparatus 10 is designed to move up and down in a piece, as the arrow shown in FIG. 1, so that the baking procedure can be carried out in the oven apparatus 10. When the substrate (not shown) such as a wafer or a panel is to be put into or taken out from the oven apparatus 10 by a main arm (not shown), the linear-motion air cylinder 15 which is connected with the shutter 14 and driven by a N2 gas is firstly used to drop the shutter 14 down, and then a control sensor (not shown) which is used to monitor the location of the shutter 14 directs the main arm to put the substrate onto the hot plate 11 of the oven apparatus 10 or take it out of the hot plate 11. After the substrate is positioned or taken away, the shutter 14 is elevated to the original location by the linear air cylinder 15.
However, because the shutter 14 is moved up and down as a whole, the temperature of the oven apparatus 10 has a variation of about 2–3° C., and thus the stability of the process is affected.
Furthermore, as shown in FIGS. 2A and 2B, under a normal condition, a gap is between the shutter 14 and the lower plate 12 as well as between the shutter 14 and the upper plate 13, respectively. However, since the shutter 14 is a hollow cuboid made by a thin stainless steel plate and has two opposite openings, the stiffness of the shutter 14 is not good and is liable to deform. That is apt to lead the shutter 14 of the conventional oven apparatus 10 in operation to rubbing against and colliding with the lower stainless steel plate 12 below the hot plate 11 as well as the upper plate above the hot plate 11, indicated by the arrows in FIGS. 3A and 3B which show an abnormal condition. The friction and collision would result in particles reducing the quality of products in the oven apparatus 10.
In addition, the shutter 14 while dropped down is also possible to have friction and impact with the fixed bases (not shown) of the lifter pins (not shown) of the oven apparatus 10, and thus pollution particles are produced and the yield of products are affected.
Therefore, an improved design of the structure of the conventional oven apparatus is desired so as to effectively solve the above-mentioned problems happened in the baking process.